NGF --> nerve growth factor
Found in a variety of peripheral tissues, nerve growth factor attracts neurites to the tissues by chemotropism, where they form synapses. The successful neurons are then protected from neuronal death by continuing supplies of nerve growth factor.
It is also found at exceptionally high levels in snake venom and male mouse submaxillary salivary glands, from which it is commercially extracted. Nerve growth factor was the first of a family of nerve tropic factors to be discovered.
amino acids 1-81 show homology with proinsulin. Besides its peripheral actions, nerve growth factor selectively enhances the growth of cholinergic neurons that project to the forebrain and that degenerate in alzheimer's disease.